<h3>Tree6</h3>
<!-- 
    nzAsyncData      是否异步加载(显示加载状态)
    nzClick          点击树节点触发
    nzExpandChange   点击展开树节点图标触发
 -->
<nz-tree [nzData]="nodes" nzAsyncData (nzClick)="nzEvent($event)" (nzExpandChange)="nzEvent($event)"> </nz-tree>